The present invention relates to an electronic blackboard having a copying function and suited to be used at a conference or the like, and more particularly to an intelligent electronic board suitable for reading characters and graphics of an original document and displaying them on a writing/drawing flat board.
An electronic blackboard having a copying function can copy on a recording paper an image of characters and graphics (hereinafter collectively called simply an image) written with a felt pen or the like on a writing/drawing flat board (hereinafter simply called a flat board) and usually is installed within a conference room or the like. This electronic blackboard is generally made of a white plate so that it is called a white board, or the name of this electronic blackboard is derived from the fact that it electronically reads an image on the flat board and copies it onto a recording paper. Similar to an ordinary blackboard using a solid particle member (chalk), the electronic blackboard has a flat board of large size to allow other persons to easily recognize an image. Different from the ordinary blackboard, the electronic blackboard has a function of copying an image on the flat board when necessary during a conference, to thereby record the proceedings of the conference or distribute copies to conference participants or clerks so as to make it unnecessary for them to write or draw the image. The electronic blackboard has another function of reading an original document such as hand-written data, general printed matters and the like and displaying them on the flat board. To read an image on the flat board and an image on an original document, a conventional electronic blackboard has been provided with a reader unit for reading an image on the flat board and another reader unit for reading an image on an original document, as disclosed in JP-A-61-47300.
The electronic blackboard disclosed therein comprises a pair of right and left rolls for winding a white board sheet having a plurality of writing surfaces, a drive mechanism for the rolls, means for photoelectrically converting information such as characters and graphics written on the sheet, means for outputting and printing the converted information, means for photoelectrically converting an image written on an ordinary paper, and means for writing the converted image information on the white board sheet. This electronic blackboard therefore has a photoelectric conversion unit for the flat board and another photoelectric conversion unit for an original document.
There is also disclosed and shown in FIG. 1 of JP-A-62-180656 a technique by which a single CCD line image sensor (shared photoelectric conversion unit) is used in common to read characters, graphics and the like on a blackboard or on an original document.
With the above-described prior art, it has been necessary to provide two independent optical systems, one for photoelectrically reading an image written on the flat board, the other for photoelectrically reading an image written on an original document. The reason for providing two optical systems is that the resolution of each photoelectric conversion element of the photoelectric conversion unit is required to be adjusted in accordance with the size of the image, which is different between the flat board and original document. The resolution herein used means the degree of fineness of pixel size, which is a minimum unit of photoelectric conversion by a photoelectric conversion unit. The resolution quantitatively means the number of lines of an image per unit length capable of being converted photoelectrically.
The resolution may be 1.4 lines/mm for an image on the flat board and 4.2 lines/mm for an image on an original document, the resolution being coarse for an image on the flat board which is larger than an ordinary original document and is generally written with large characters or graphics to allow visual recognition from a remote place.
Another reason for providing two optical systems is the concept that an operation panel should be mounted in front of the flat board. Accordingly, the original reader unit and its operation panel have been mounted at the area where a chalk saucer is located. Specifically, the flat board reader unit is mounted at the side end portion of the flat board, and the original document reader unit is mounted in front of the flat board. This concept arises from an adherence to the view that the operation panel should be mounted in front of the apparatus, similar to the operation panel of a copying machine, image scanner (image reader) or the like.
Provision of two optical systems results in an optical system which is bulky and high cost, and requires precise adjustment of the mechanical components thereof (e.g., image sensor array, optical lens, light source lamp, mechanism for holding these elements, and the like), and long adjustment time. These factors have restricted the total cost of the white board.
A conventional white board is of a stand-alone type so that electrical signals of an image are used only within the white board. Therefore, there is no mutual connection between white boards. It often becomes inconvenient if only a single white board is provided at the conference with a number of participants. Even if a plurality of white boards are used, the same image is required to be written on the plurality of white boards, thereby taking a long time for image writing. Further, a conventional white board, although it has a copying function, cannot change or edit as desired an image once inputted, the change or editing of an image including such as layout, enlargement, reduction, rotation, reversal (inclusive of negative/positive reversal) and the like.